Alan Neil | Founder & CEO | ASN Associates

Since the 1990s, silver has been so frequently incorporated into advanced wound care dressings, silver-containing formats are now available in virtually the entire range of advanced wound dressings. But what is it that has made silver such a popular feature for wound care dressings?

The short answer is that silver works—something that has been known for a very long time. In past centuries, silver has been used in drinking and storage vessels to prevent spoilage. More recently, silver—and silver compounds such as silver sulphadiazine and silver nitrate—have been adopted by the medical community because of its ability to:

• Prevent infections

• Sterilize medical devices

• Discourage the formation of biofilms in heart valves, endotracheal tubes and catheters.

Yet, despite its popularity and versatility, the benefits claimed for silver in wound dressings—and the mechanisms that deliver these benefits—still maintain some controversy and will probably not be totally resolved in the near future.

An Atomic Appreciation of Silver

The active antimicrobial agent associated with silver is the positive silver ion (Ag⁺). This ion has an oligodynamic effect, meaning that extremely low concentrations are required.

The ion is short-lived and can be easily removed from a solution by combining it with negative ions (Cl^-). The ion readily binds with many microbial structures, proteins and nucleic acids, enabling it to inactivate microbes by several different pathways at once. This is thought to greatly reduce the opportunity for infectious agents to develop resistance to the actions of silver, and it contributes to its broad spectrum of activity.

Getting the Silver Into Silver Wound Dressings

Silver is incorporated into wound dressings as elemental silver (e.g., Acticoat^®, Silverlon^®, MediPlus™ Foam Ag) or as a component of various silver salts (e.g., silver sulphadiazine, silver lactate).

To be effective, the silver element or compound must be moistened with water or exudate to release the silver ion. Elemental silver is not very soluble, so it must be presented over a large surface area (such as with fibers or nets) to insure the dissociation of a sufficient number of ions.

Silver salts vary in their dissociation constant and are easier to incorporate into foams, hydrocolloids and hydrogels. Silver dressings can contain a large reservoir of silver, allowing continuous replacement of ions as they are taken up by microbes and inactivated by other components of the wound fluid. The long-acting effect supports longer intervals between wound dressing changes and less disturbance of wound healing.

Silver Wound Dressing Studies and Toxicity

Silver wound dressing studies have compared the amounts of silver in a dressing and the rate of silver release in-vitro, but this kind of data often shows poor correlation with a dressing’s activity, suggesting that several variables are in play. Apparently, once effective levels of silver are reached, excess ions have little additional activity, and that speed of release is less important a factor in the time/dose effect than might be seen in the in-vitro studies.

In-vivo, however, the fluid and biological environment in which ions are released are vastly different. It would be anticipated that in-vitro ionization would be less than in an aqueous solution and that ion removal would be faster and greater. Sufficient levels of silver ion constantly replaced during use would appear to provide optimal performance.

The toxic effects of silver to human cells are well documented and understood. Many observations are based on high blood and tissue levels that may occur in burn patients where a large body area may be covered with silver sulfadiazine for extended periods. In most cases, silver is cleared from the body over time and without toxic effects. The amount presented for systemic absorption by advanced wound care dressings in considerably less.

Silver Wound Dressings and Bioburden Reduction

Although there are few randomized controlled studies that achieve statistical significance in showing a reduction in the infection rate associated with the use of silver wound dressings, ample clinical evidence indicates they are associated with reduction in pain, reduction in odor, and improved quality-of-life measures.

Silver-containing wound dressings have been shown to reduce wound complications and to reduce the occurrence of critical colonization when compared to the same materials without silver. Further, Silver wound dressings are associated with reduced inflammation, increased rate of healing and reduction in biofilm formation.

The observed benefits are thought to result from silver’s broad spectrum of antimicrobial activity helping to control bioburden. The antimicrobial action may provide benefit at the wound-dressing interface and within the dressing where fluid-containing pathogens are sequestered. Reduction in bioburden improves the wound-healing environment by reducing competition for resources and the production of toxic metabolites. With fewer pathogens present, inflammation due to critical colonization may be sufficiently reduced to allow the wound to progress unimpeded to the proliferative phase of healing.

With silver available in a large number of advanced wound care products, the selection of a wound dressing can be optimized for the type and condition of the wound, with the silver component providing the extra security derived from broad-spectrum antimicrobial activity. Reduction in bioburden may result in:

• Reduced inflammatory response (including a reduction in MMP generation and activity)

• Reduced exudation

• Reduced pain

• Removal of many of the factors that impede the healing of chronic wounds

In conclusion, silver dressings offer the health care professional a valuable tool for use in treating acute, chronic and difficult wounds. The availability of new cost-effective wound care products allows their benefits to be extended to a larger population of patients.

Tags: Medical Devices | Medical Products Read More

To anybody whose professional life is in some way connected to wound care dressings, last month’s announcement that MediPlus expanded its portfolio to include silver (Ag) dressings was likely recognized as a very important headline. But why is it so important to offer silver? One way to appreciate this is to understand the evolution of wound care dressings, since many of the products in that evolutionary timeline are still sold and used today.

There have been several critical milestones in the evolution of wound care that have lead to noticeable improvements in treatment outcomes. Each step reflects a better understanding of the needs of the wound and the needs of the patient, which, when supported, have lead to an increase in the quality, speed and reliability of wound healing. Each step forward has led to a new plateau of improvement, which in turn has served as the new baseline for standards of care. In most instances, the step involved the recognition of a barrier to healing and the adoption of means to overcome that barrier.

Let There be Gauze!

Looking back approximately 100 years ago, it was an era when gauze was the first choice for wound care dressing. This era represents the first baseline and lengthiest plateau in the wound care dressing evolution.

Wounds underwent surgical, mechanical enzymatic or chemical debridement to expose viable tissue. Dry or saline-moistened gauze that was changed several times a day and packed into the wound was often accompanied by the liberal use of antiseptics at each dressing change. Under these gauze protocols, healing was frequently disrupted since multiple daily dressing changes and moist gauze enabled a direct route for microbial colonization of the wound.

Licking a Wound with Moist Wound Dressings

It would eventually be discovered that the first “advanced” moist wound dressings—transparent films—could seal the wound from further contamination and allow the natural exudate to support the physiology of wound healing

Dressing options would soon rapidly evolve to optimize moisture levels and conform to wound surfaces in ever more efficient ways. For example, dressings were left in place longer, reducing the mechanical and thermal disruptions to the healing process, reducing time to healing, and the resources expended on dressing changes. As the wound began to heal, the dressing selection could be modified to provide optimal moisture levels for healing at each stage and to reflect the changes associated with the wounds progression.

The practice of moist wound healing after wound debridement soon became state-of-the-art, and with the introduction of hydrogels, it provided an alternative to surgical and mechanical debridement. Consequently, most wounds could now be managed by non-physician practitioners at lower cost and with dramatic increases in success.

How Compression Caused an Expansion in Wound Dressings

Moist wound healing and advanced wound care represented a new healing plateau of wound care that lasted with minor changes for decades. The next evolution came from the recognition that different wound etiologies required targeted adjuvant therapy to get to the next level of healing.

The most dramatic demonstration of this philosophy came with the adoption ofcompression to support the healing of venous stasis ulcers. Once compression was accepted as a best practice, the methods to deliver effective compression proliferated from four-layer elastic to two-layer short stretch, with phenomenal changes documented in healing outcome.

Additionally, etiology focus directly improved the outcome of other chronic wound groups by demonstrating the dramatic efficacy of total contact casting for neuropathic diabetic foot ulcers and pressure relief for pressure ulcers.

Once wound etiology was addressed (e.g. restoration of circulation) and a moist wound environment was provided, additional barriers to healing became apparent. Two key related concepts arose that focused attention back to the local conditions within the wound: matrix metalloproteinases (MMPs), which surfaced as a hot topic of discussion and research, and critical colonization came forward to account for wounds stalled in the inflammatory stages of healing.

Solving the Riddle of Critical Colonization with Advanced Wound Dressings

Although all wounds might have been seen as colonized, not all colonized wounds progressed to infection, and not all colonized wounds healed routinely. Instead, as many wounds would stall in the inflammatory stage of healing, it became apparent that one of the factors involved in this barrier to healing was the presence of microbes in sufficient quantities to stimulate a chronic inflammatory response by the host.

The concept of critical colonization was recognized as a state between contamination levels that were managed and resolved by host defenses and full-blown infection with the classic signs of heat, redness, swelling and pain. The objective soon became one of shifting bioburden within the wound (i.e., the number of organisms and their toxic products) back towards levels below those that generated a chronic inflammatory state and away from the serious risk and expense involved with wound inflection.

Silver Dressings Becomes a Gold Standard

The routine use of antiseptics as prophylaxis against infection had declined dramatically as study of the stages and physiology of wound healing revealed their toxic effect on cells and the processes required for healing. Local antibiotics were known to have limited spectra of activity, with the potential to generate resistant microbial strains. Of utmost importance was the fact that neither worked well with the advanced wound care dressings, bandaging systems or TCC that had become so important in supporting efficient wound repair.

Silver, by comparison, had a long history as an antimicrobial agent from its use in silver-coated vessels in ancient times to reduce the spoilage of wine and water. It had also demonstrated great success in helping to prevent infection in burn patients when it was formulated as silver sulphadiazine cream.

Silver could be readily incorporated into advanced wound care dressings as elemental silver (e.g., Acticoat®, Silverlon®) or in any number of silver compounds (silver lactate). Silver dressings preserved the beneficial properties of advanced wound care moisture interactive dressings while adding antimicrobial activity to stop microbial populations progressing from contamination to critical colonization to infection. Silver also provided effective antimicrobial action, a broad spectrum of coverage with low cytotoxicity and the long duration of action required for efficacy under bandaging and advanced wound care dressings.

Ultimately, the evolution of wound care dressings that would manifest with a rapid adoption of silver wound care dressings would also signify acknowledgement that the prevention of infection and critical colonization has beneficial consequences on the speed and cost of wound healing treatment.

The Real Value of Silver

Although silver dressings are more expensive to produce—and in turn cost more for a treatment center—they are treated as standard wound dressings under the HCPCS Level II reimbursement system.

Inexplicably, silver foam dressings are reimbursed at the same rate as non-silver foam dressings. However, obtaining FDA 510(k) marketing approval for silver dressings has now become a more intensive and costly process, requiring significantly more supporting clinical and laboratory data.

Wound care dressing manufacturers with the most recent 510(k) clearances meet the new standards demanded by the FDA. Manufacturers of older established products should be challenged to document similar performance parameters before being considered for use in the clinic.

MediPlus’ Silver Foam dressings were recently cleared by the FDA under these new standards. MediPurpose is now marketing these dressings at a very competitive price point to be more affordable, and thus more widely available in appropriate treatment settings to a larger patient population.

Do you use or sell silver wound dressings? What are your opinions about their efficacy and value?

Tags: Medical Device Innovation Read More

Having spent more than 30 years intimately involved in the development and marketing of medical products (such as wound dressings), I find the history of innovation in the wound care field to be of great interest.

Although wound care dressings have existed for decades, the 1980s were a pivotal time for wound care products. The few wound dressing categories that existed were dominated by a few large companies that heavily promoted their technology for the hole in the patient. For instance, ConvaTec pushed their hydrocolloid technology (developed for ostomy applications) against all other substrates and claimed higher healing power versus competitors. Smith & Nephew pushed foams, and Carrington championed hydrogels as the best product for wounds.

As medical product companies were devoting more attention to wound care, it soon became apparent that there was more to treating the wound than the wound itself. As a result, their attentions broadened to include skin care and incontinence management, and the major wound care competitors began snapping up the major skin care manufacturers. For example, Calgon Vestal and Sween skin care lines were added to the dressing lines of ConvaTec and Coloplast.

The Rise of Wound Care Product Categories and Perceived Advantages

As wound care dressing categories evolved, so did the role of dressing healing studies. Although these studies had always compared different wound care products from start of treatment to healing, they also began to indicate different product classes’ advantages for different stages of wound healing.

For instance, studies started to indicate that hydrogels might be excellent selections for autolytic debridement of eschar, while alginates or foams might be excellent selections to fill cavities and manage high levels of exudate during the inflammatory phase of deeper wounds. As healing progressed and wound depth decreased with production of granulation tissue, more appropriate product selection might shift to hydrocolloid and eventually transparent films as a secondary and then primary dressing.

Value Prop Priorities: Price and Ease of Acquisition vs. Quality

This evolution soon began to impact the medical supply industry’s landscape. The dominant players began to add several—or all—wound care product categories to their lines as they evolved from specialty product promoters to one-stop-shop providers of all products required for wound care. Consequently, clinics and hospitals could now purchase all categories of dressing from several large providers and bundle their purchases to control cost of acquisition.

As dominant corporations added categories to their lines, the marginal differences between products within a dressing class were rarely considered. Practitioners were exposed to various competing hydrocolloids as the institutional supply contract shifted between major players, and they came to realize that none possessed superior healing benefits over others of similar quality.

Further, the source of the hydrocolloid, foam or other dressings became less important that the cost and ease of acquisition and the selection of products needed by the clinic. Anyone with solid wound care knowledge and good connections with medical product converters could have a product line produced that included the most frequently used dressing classes and the number of “full line” suppliers expanded dramatically.

There’s More Room Than You Think

In such a market, the need for yet another supplier of advanced wound care dressings would appear limited. So, a couple years ago when MediPurpose first asked me if I thought it would be a good idea to introduce a new line, my immediate reaction was to advise that since the market was already saturated with so many established players, MediPurpose’s chances for significant market penetration was minimal.

I suggested that unless they offered a full line of wound care products with high quality that matched the market leaders at a significant cost advantage, they would probably be better served investing time and dollars elsewhere. However, I did agree to take a closer look at what would eventually become their MediPlus™ Advanced Wound Care product line and the process MediPurpose uses to select new medical products for potential investment and development.

A review of each product class and each line item within the class quickly showed that the company had managed to acquire well-made wound care products with the handling characteristics most appreciated in clinical use. Others may be able to supply as broad a product line, but few can match MediPlus’ depth of product line offerings by size and application.

Given they had the required quality and breadth of line, the key remaining issue was whether they could bring the MediPlus brand to market at price points that could encourage customers to evaluate the wound care products and switch when performance met expectations. However, MediPurpose has been successful in partnering with truly low-cost and high-quality producers, and it does not incur the expense of a large sales and marketing staff to promote the MediPlus line.

Today in the 2010s when clinic costs are rising and reimbursement has stagnated or declined, the MediPlus Advanced Wound Care line can indeed fulfill dressing requirements while significantly reducing costs and returning profits to its customers.

Sounds like a recipe for success for all.

Tags: Medical Devices | Medical Products Read More